CN209746179U - novel high-efficiency multi-mode converter - Google Patents
novel high-efficiency multi-mode converter Download PDFInfo
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- CN209746179U CN209746179U CN201920022493.7U CN201920022493U CN209746179U CN 209746179 U CN209746179 U CN 209746179U CN 201920022493 U CN201920022493 U CN 201920022493U CN 209746179 U CN209746179 U CN 209746179U
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- 230000003287 optical effect Effects 0.000 claims abstract description 16
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- 238000006243 chemical reaction Methods 0.000 claims description 24
- 230000008878 coupling Effects 0.000 claims description 17
- 238000010168 coupling process Methods 0.000 claims description 17
- 238000005859 coupling reaction Methods 0.000 claims description 17
- 238000005516 engineering process Methods 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 230000008054 signal transmission Effects 0.000 claims description 4
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 238000004891 communication Methods 0.000 abstract description 8
- 238000000034 method Methods 0.000 abstract description 5
- 230000009466 transformation Effects 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 description 17
- 239000013307 optical fiber Substances 0.000 description 9
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- 230000007423 decrease Effects 0.000 description 2
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- 230000000694 effects Effects 0.000 description 1
- 239000004038 photonic crystal Substances 0.000 description 1
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Abstract
the utility model relates to a novel high efficiency multi-mode converter, the high efficiency transform of basic mode signal (LP01) to a plurality of high order modes (LPmn) of specifically realizing the multiplexing technique of mode belongs to the optical communication field. The utility model discloses a: a core cladding (1), "a radius-decreasing tapered core (2)," a radius-increasing tapered core (3) ". The radius-decreasing tapered fiber core (2) and the radius-increasing tapered fiber core (3) form a multi-mode converter realized by the reverse tapered double-core structure optical waveguide. High-order modes (LPmn) are coupled out of the radius-increasing tapered core (3) by injecting a fundamental mode signal (LP01) from the radius-decreasing tapered core (2). The utility model discloses a be applied to optical communication mode multiplexing technique, realize multi-mode converter specifically, can realize the high efficiency transformation of basic mode signal (LP01) to a plurality of high order modes (LPmn); likewise, the transformation of the high-order mode (LPmn) into the fundamental mode signal (LP01) can also be achieved.
Description
Technical Field
The invention relates to a novel high-efficiency multi-mode converter, which can realize the conversion of four high-order modes at 1550 nm wavelength by adjusting structural parameter values, and belongs to the technical field of optical fiber mode multiplexing communication.
Background
the optical fiber mode multiplexing (MDM) technology is a main method for realizing optical fiber Multiple Input Multiple Output (MIMO) communication, and is the most direct and effective method for increasing the transmission capacity of an optical fiber link.
The optical fiber mode multiplexing communication system transmits signals by using different transmission modes in a few-mode fiber (FMF), wherein each transmission mode is used as an independent channel and independently carries one transmission signal. When the mode multiplexing communication technology is used, a basic mode signal (LP01) at a transmitting end needs to be converted into a high-order mode (LPmn) and multiplexed in a few-mode optical fiber for transmission; similarly, the high-order mode (LPmn) carrying information at the receiving end needs to be converted into the fundamental mode signal (LP01) and then signal-processed.
the mode converters used in the mode multiplexing technique so far are mainly of the following types: the device comprises a geometrical optical mode converter, a mode multiplexer/demultiplexer based on a planar optical waveguide, a long-period fiber grating type mode converter, a mode converter based on a photonic crystal fiber and a coupler of a double-core fiber. These studies are either oversized and not conducive to system integration; or low conversion efficiency; or only a conversion of one higher order mode is implemented.
The novel high-efficiency multi-mode converter designed by the invention is searched by documents, and the same public reports as the invention are not found.
disclosure of Invention
Aiming at the defects of the existing mode conversion technology, the mode converter is formed by adopting the reverse tapered double-core structure optical waveguide, the fundamental mode signal (LP01) is converted into a plurality of high-order modes (LPmn), and the conversion efficiency is high. The novel high-efficiency multi-mode converter can realize the conversion of four high-order modes at 1550 nm wavelength efficiently by adjusting the structural parameter values, and can also realize the conversion of the high-order mode (LPmn) to a fundamental mode signal (LP 01). And the structure is simple, the size is small, and the system integration is facilitated.
the invention realizes a multi-mode converter for converting a fundamental mode signal (LP01) into a high-order mode (LPmn) by arranging a radius-decreasing tapered fiber core (2) and a radius-increasing tapered fiber core (3) in parallel and aligning two ends to form a mode converter formed by a reverse tapered double-core structure optical waveguide.
The invention relates to a novel high-efficiency multi-mode converter, which comprises: a core cladding (1), "a radius-decreasing tapered core (2)," a radius-increasing tapered core (3), "wherein:
a. The fiber core cladding (1) uniformly covers the fiber core, the radius is R1, and the length is L;
The length of the radius-reduced tapered core (2) is L, and the radius of the core is gradually reduced from R2 to R3; the length of the radius-increasing type tapered core (3) is L, and the radius is slowly increased from R4 to R5;
The central axes of the radius-decreasing tapered fiber core (2) and the radius-increasing tapered fiber core (3) are parallel, and the distance between the central axes is D;
d. The refractive index of the core cladding (1) is n1, the refractive indices of the radius-decreasing tapered core (2) and the radius-increasing tapered core (3) are both n2, and n1 is less than n 2;
e. A fundamental mode signal (LP01) is input into the radius-decreasing tapered core (2) from a fundamental mode input port (P1), and is coupled by the radius-increasing tapered core (3), so that an input mode is converted into a high-order mode and is output from a coupling output port (P4);
f. Along with the transmission of signals, the effective refractive index of a basic mode in the radius-decreasing tapered fiber core (2) is gradually reduced, the effective refractive index of a coupled-out high-order mode in the radius-increasing tapered fiber core (3) at the coupling output end is increased, and when the effective refractive index of a certain mode is equal to that of the basic mode, the power of the basic mode is greatly coupled to the high-order mode, so that the high-efficiency mode conversion is realized.
g. The length L and the radiuses R2 and R3 of a basic mode input port (P1) and a basic mode output port (P2) of the radius reduction type tapered fiber core (2) are adjusted, the distance D of the central axis is increased, and the radiuses R4 and R5 of a coupling input port (P3) and a coupling output port (P4) of the radius increase type tapered fiber core (3) are increased, so that the basic mode signal (LP01) can be converted to a higher-order mode;
h. The optical waveguide structure is round, or rectangular; when a rectangular waveguide is used, the mode conversion results in quasi-LPmn rather than strict LPmn mode;
i. The mode converter is realized on the silicon dioxide planar optical waveguide circuit technology.
The novel high-efficiency multi-mode converter can realize the conversion of four high-order modes at 1550 nm wavelength efficiently by adjusting the structural parameter values, and can also realize the conversion of the high-order mode (LPmn) to a fundamental mode signal (LP 01). And the structure is simple, the size is small, the system integration is facilitated, and the optical fiber mode multiplexing communication system has a huge application prospect in the future.
Drawings
Fig. 1 is a structural view of a mode converter.
fig. 2 shows the effective refractive index of the fundamental mode signal (LP01) and the high-order mode (LP11) as a function of transmission distance.
Fig. 3 shows the normalized power of the fundamental mode signal (LP01) and the higher order modes (LP11) as a function of transmission distance.
fig. 4 shows the normalized power of the fundamental mode signal (LP01) and the higher order modes (LP21) as a function of transmission distance.
Fig. 5 shows the normalized power of the fundamental mode signal (LP01) and the higher order modes (LP31) as a function of transmission distance.
Fig. 6 shows the normalized power of the fundamental mode signal (LP01) and the higher order modes (LP12) as a function of transmission distance.
Detailed Description
the invention provides a novel high-efficiency multi-mode converter for converting a fundamental mode signal LP01 into a high-order mode LPmn, aiming at the defects of the conventional mainstream mode conversion technology. The novel high-efficiency multi-mode converter provided by the invention can realize the conversion of four high-order modes at 1550 nm wavelength efficiently by adjusting the structural parameter values, and can also realize the conversion of the high-order mode LPmn to a fundamental mode signal LP 01. And the structure is simple, the size is small, and the system integration is facilitated.
The invention realizes a multi-mode converter which converts a fundamental mode signal (LP01) into different high-order modes LPmn by arranging the radius-decreasing tapered fiber core 2 and the radius-increasing tapered fiber core 3 in parallel and aligning two ends to form a mode converter formed by a reverse tapered double-core structure optical waveguide.
the invention relates to a novel high-efficiency multi-mode converter, which comprises: fiber core cladding 1, "radius reducing type tapered fiber core 2", "radius increasing type tapered fiber core 3", wherein:
a. The fiber core cladding 1 uniformly covers the fiber core, the radius is R1, and the length is L;
The length of the radius reducing tapered fiber core 2 is L, and the fiber core radius is slowly reduced from R2 to R3; the length of the radius-increasing type tapered fiber core 3 is L, and the radius is slowly increased from R4 to R5;
the central axes of the radius reducing type tapered fiber core 2 and the radius increasing type tapered fiber core 3 are parallel, and the distance between the central axes is D;
d. the refractive index of the core cladding 1 is n1, the refractive indices of the "radius-decreasing tapered core 2" and the "radius-increasing tapered core 3" are both n2, and n1< n 2;
e. A fundamental mode signal LP01 is input into the radius-decreasing tapered fiber core 2 from the fundamental mode input port P1, the input mode is converted into a high-order mode through the coupling of the radius-increasing tapered fiber core 3, and the high-order mode is output from the coupling output port P4;
f. Along with the transmission of signals, the effective refractive index of a basic mode in the radius-decreasing tapered fiber core 2 is gradually decreased, the effective refractive index of a high-order mode coupled and output in the radius-increasing tapered fiber core 3 at the coupling output end is increased, and when the effective refractive index of a certain mode is equal to that of the basic mode, the power of the basic mode is greatly coupled to the high-order mode, so that high-efficiency mode conversion is realized.
g. The length L and the radiuses R2 and R3 of the base mode input port P1 and the base mode output port P2 of the radius reduction type tapered fiber core 2 are adjusted, the distance D between the central axes is increased, and the radiuses R4 and R5 of the coupling input port P3 and the coupling output port P4 of the radius increase type tapered fiber core 3 are increased, so that the base mode signal LP01 can be converted to a higher-order mode
h. The optical waveguide structure is round, or rectangular; when a rectangular waveguide is used, the mode conversion results in quasi-LPmn rather than strict LPmn mode;
i. The mode converter is realized on the silicon dioxide planar optical waveguide circuit technology.
The invention relates to a novel high-efficiency multi-mode converter, which is a mode multiplexing technology applied to the field of optical communication. The structure is shown in fig. 1.
the technical scheme of the invention is realized as follows: the transmission constant of the transmission mode in the optical fiber completely represents the mode, and the transmission constant is determined by the effective refractive index of the mode, therefore, by reasonably designing the dual-core structure, along with the transmission of signals, the effective refractive index of the basic mode in the radius-decreasing tapered fiber core 2 is gradually decreased, the effective refractive index of the coupled-out high-order mode in the radius-increasing tapered fiber core 3 at the coupling output end is increased, when the effective refractive index of a certain mode is equal to the effective refractive index of the basic mode, the power of the basic mode is greatly coupled to the high-order mode, and the high-efficiency mode conversion is realized.
The mode converter described above is further illustrated with reference to fig. 2 and 3, taking as an example a mode converter for converting LP01 to LP 11. Fig. 2 shows the effective refractive index of the fundamental mode signal LP01 in the "radius-decreasing tapered core 2" and the high-order mode LP11 in the "radius-increasing tapered core 3" as a function of transmission distance. When the LP01 mode (fundamental mode) is injected from the input, the effective index of the LP01 mode (shown as a solid line in fig. 2, Neff01) also decreases slowly as the core radius is slowly tapered, while in the "radius-increasing tapered core 3", the effective index of the LP11 mode (shown as a dashed line in fig. 2, Neff11) increases slowly as its radius is slowly tapered. At a transmission distance of about 5000 microns, the effective index of the LP01 mode and the effective index of the LP11 mode are equal, and thus the power of the LP01 mode is largely converted into the LP11 mode even when the coupling is fast and severe. Then the effective refractive indexes of the two modes are gradually inconsistent, the coupling effect tends to be moderate, and finally the power of the LP01 mode is almost completely coupled into the LP11 mode and transmitted in a high-order mode, so that the conversion from the basic mode to the high-order mode of the optical fiber is realized. In conjunction with the variation of the normalized power of the mode in fig. 3, the LP01 mode power decreases sharply and the LP11 mode power increases sharply when the transmission distance reaches 5000 microns. Eventually, the power of LP11 mode reaches 0.99, almost completely achieving mode conversion.
The conversion of the fundamental mode signal LP01 to a higher-order mode (relative to the currently realized converted LP11 mode) can be realized by adjusting the lengths L and the radii R2 and R3 of the fundamental mode input port P1 and the fundamental mode output port P2 of the radius-reducing tapered core 2, increasing the radii R4 and R5 of the coupling input port P3 and the coupling output port P4 of the radius-increasing tapered core 3, and simultaneously increasing the distance D between the central axes thereof. Fig. 4, 5 and 6 show the normalized power as a function of transmission distance for the fundamental mode signal (LP01) and for three different higher order modes (LP21, LP31 and LP12, respectively). As can be seen from fig. 4, 5 and 6, finally, the normalized power of the high-order modes LP21, LP31 and LP12 at the output end is-0.96, -0.92 and-0.93, respectively, i.e. high conversion efficiencies of-96%, 92% and-93% are achieved, respectively.
Here, the transformation of LP01 to LP11, LP21, LP31, and LP12 modes is shown; in practice, however, the adjustment of the values of the structural parameters as described above may also be used to effect the conversion of the LP01 mode to other higher order modes LP41, LP22, etc., at the 1550 wavelength.
While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
Claims (6)
1. a novel high efficiency multimode converter characterized by: adopt reverse tapering twin-core structure optical waveguide to constitute mode converter, include: a core cladding (1), "a radius-decreasing tapered core (2)," a radius-increasing tapered core (3), "wherein:
a. The fiber core cladding (1) uniformly covers the fiber core, the radius is R1, and the length is L;
the length of the radius-reduced tapered core (2) is L, and the radius of the core is gradually reduced from R2 to R3; the length of the radius-increasing type tapered core (3) is L, and the radius is slowly increased from R4 to R5;
the central axes of the radius-decreasing tapered fiber core (2) and the radius-increasing tapered fiber core (3) are parallel, and the distance between the central axes is D;
d. The refractive index of the core cladding (1) is n1, the refractive indices of the radius-decreasing tapered core (2) and the radius-increasing tapered core (3) are both n2, and n1 is less than n 2.
2. a novel high efficiency multimode converter according to claim 1, characterized in that: a fundamental mode signal (LP01) is input from a fundamental mode input port (P1) to the radius-decreasing tapered core (2), and is coupled to the radius-increasing tapered core (3) to convert the input mode into a high-order mode, which is output from a coupling output port (P4).
3. A novel high efficiency multimode converter according to claim 1, characterized in that: along with the transmission of signals, the effective refractive index of a basic mode in the radius-decreasing tapered fiber core (2) is gradually reduced, the effective refractive index of a coupled-out high-order mode in the radius-increasing tapered fiber core (3) at the coupling output end is increased, when the effective refractive index of a certain mode is equal to that of the basic mode, the power of the basic mode is coupled to the high-order mode, and high-efficiency mode conversion is realized.
4. A novel high efficiency multimode converter according to claim 1, characterized in that: by adjusting the length L and the radiuses R2 and R3 of the fundamental mode input port (P1) and the fundamental mode output port (P2) of the radius reduction tapered fiber core (2), the distance D of the central axis is increased, and the radiuses R4 and R5 of the coupling input port (P3) and the coupling output port (P4) of the radius increase tapered fiber core (3) are increased, so that the fundamental mode signal (LP01) can be converted to a higher-order mode.
5. a novel high efficiency multimode converter according to claim 1, characterized in that: the optical waveguide structure is round, or rectangular; when rectangular waveguides are used, the mode conversion results in quasi-LPmn rather than the strict LPmn mode.
6. a novel high efficiency multimode converter according to claim 1, characterized in that: the mode converter is realized on the silicon dioxide planar optical waveguide circuit technology.
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| CN201920022493.7U CN209746179U (en) | 2019-01-07 | 2019-01-07 | novel high-efficiency multi-mode converter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109459819A (en) * | 2019-01-07 | 2019-03-12 | 云南大学 | Efficient multi-mode converter |
| CN111796359A (en) * | 2020-07-31 | 2020-10-20 | 燕山大学 | Double-core optical fiber mode converter |
| CN112394506A (en) * | 2020-07-23 | 2021-02-23 | 江南大学 | Design method of silicon-based modular order converter based on surface plasmon polariton |
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2019
- 2019-01-07 CN CN201920022493.7U patent/CN209746179U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109459819A (en) * | 2019-01-07 | 2019-03-12 | 云南大学 | Efficient multi-mode converter |
| CN109459819B (en) * | 2019-01-07 | 2023-09-12 | 云南大学 | Efficient multimode converter |
| CN112394506A (en) * | 2020-07-23 | 2021-02-23 | 江南大学 | Design method of silicon-based modular order converter based on surface plasmon polariton |
| CN111796359A (en) * | 2020-07-31 | 2020-10-20 | 燕山大学 | Double-core optical fiber mode converter |
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